Naphthalenedicarboxylic acid containing polymer compositions having reduced fluorescence

ABSTRACT

This invention relates to naphthalenedicarboxylic acid containing polymer compositions having reduced fluorescence. More specifically, the polymers contain at least 0.1 mole percent of 2,6-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylate ester, with 0.1 to 5 mole percent of a copolymerizable aromatic ketone. These polymers are useful for packaging applications where clarity and/or aesthetic appeal are of concern.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/103,645, filed Aug. 9, 1993, now U.S. Pat. No. 5,310,837.

FIELD OF THE INVENTION

This invention relates to naphthalenedicarboxylic acid containingpolymer compositions having reduced fluorescence. More specifically, thepolymers contain at least 0.1 mole percent of2,6-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylate ester,with 0.1 to 5 mole percent of a copolymerizable aromatic ketone. Thesepolymers are useful for packaging applications where clarity and/oraesthetic appeal are of concern.

BACKGROUND OF THE INVENTION

Naphthalenedicarboxylic acid is used to make extrusion andinjection-molding resins because of the good heat resistance, high glasstransition temperature, and gas barrier properties ofnaphthalenedicarboxylic acid based polymers. Polymers containingnaphthalenedicarboxylic acid are used in the fabrication of variousarticles for household or industrial use, including appliance parts,containers, and auto parts. One major drawback ofnaphthalenedicarboxylic acid containing polymers, however, is theirinherent bluish fluorescence. Thus, objects prepared withnaphthalenedicarboxylic acid containing polymers have a hazy and bluishappearance. This phenomenon is especially of concern in the packaging offoods and beverages wherein the food or beverage inside a container madefrom a naphthalenedicarboxylic acid containing polymer appearsunnatural.

The fluorescence of homopolymers of poly(ethylene2,6-naphthalenedicarboxylate), referred to as PEN, is known in the art.Because of the improved properties of naphthalenedicarboxylic acidcontaining polymers, it is desirable to incorporate small amounts ofnaphthalenedicarboxylic acid in polymers such as poly(ethyleneterephthalate) (PET). However, copolymers containing very small amountsof naphthalenedicarboxylic acid fluoresce with intensity similar to, orin some cases greater than PEN homopolymers. Surprisingly, PET modifiedby copolymerizing in less than 1 mole percent naphthalenedicarboxylicacid has significant visible fluorescence.

Fluorescence is a type of luminescence in which an atom or moleculeemits radiation in passing from a higher to a lower electronic state.The term is restricted to phenomena in which the time interval betweenabsorption and emission of energy is extremely short (10⁻¹⁰ to 10⁻⁶second). Fluorescence in a polymer or small molecule, occurs when aphoton is emitted from an excited singlet state. Quenching offluorescence eliminates or reduces the ability for photon emission byproviding an alternative pathway for the excited state energy such asvibronic or heat loss, or intersystem crossing to the excited tripletstate.

Methods to quench fluorescence in PEN have been disclosed by ChenShangxian et al. in an article entitled, "Fluorescence Spectra OfPoly(Ethylene-2,6-Naphthalene Dicarboxylate)" which appeared in SCIENTIASINICA, Vol. XXIV, No. 5, May 1981, and by CAO Ti et al. in an articleentitled, "Intermolecular Excimer Interaction In Poly(PolytetramethyleneEther Glycol Aryl Dicarboxylate)" which appeared in ACTA CHIMICA SINICA,Vol. 42, No. 1, 1984. Both of the references disclose the use ofo-chlorophenol to quench PEN fluorescence in a chloroform solution.Dissolving the PEN in a chloroform solution to disperse the fluorescencequencher therein, however, is not practical on an industrial scalebecause only very dilute PEN solutions can be prepared. In addition, thePEN must have a low molecular weight to dissolve in the chloroformsolution.

In contrast, the present inventors have unexpectedly determined that theincorporation of 0.1 to 5 mole percent of a copolymerizable aromaticketone in polymers containing naphthalenedicarboxylic acid significantlyreduces fluorescence without deleteriously affecting the physicalproperties of the polymer.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to providenaphthalenedicarboxylic acid containing polymer compositions withreduced fluorescence.

Accordingly, it is another object of the invention to providenaphthalenedicarboxylic acid containing polymer compositions which havereduced fluorescence and are useful in applications where good heatresistance, high glass transition temperature and gas barrier propertiesare required.

These and other objects are accomplished herein by anaphthalenedicarboxylic acid containing polymer composition with reducedfluorescence comprising repeat units from:

(a) a dicarboxylic acid component which comprises at least 0.1 molepercent of 2,6-naphthalenedicarboxylic acid or2,6-naphthalenedicarboxylate esters;

(b) a diol or diamine component; and

(c) 0.1 to 5 mole percent, based on 100 mole percent dicarboxylic acidand 100 mole percent diol or diamine, of a copolymerizable aromaticketone which has at least one acyl group directly attached to thearomatic ring.

DESCRIPTION OF THE INVENTION

The polymers of the present invention contain naphthalenedicarboxylicacid and a fluorescence quenching compound. The polymers contain repeatunits from a dicarboxylic acid, a diol or a diamine, and acopolymerizable aromatic ketone. The dicarboxylic acid, component (a),consists of at least 0.1 mole percent 2,6-naphthalenedicarboxylic acidor 2,6-naphthalenedicarboxylate ester. The diol or diamine, component(b), may be any diol or diamine. The copolymerizable aromatic ketone,component (c), consists of 0.1 to 5 mole percent, based on 100 molepercent dicarboxylic acid and 100 mole percent diol or diamine, of acopolymerizable aromatic ketone diacid, diester, or diol. Preferably,the polymer is a polyester containing repeat units from 0.1 to 100 molepercent of 2,6-naphthalenedicarboxylic acid or2,6-naphthalenedicarboxylate ester, and 0 to 99.9 mole percent ofterephthalic acid or dimethyl terephthalate, and at least 90 molepercent ethylene glycol.

The dicarboxylic acid component of the polymer may optionally includeone or more different monomers other than 2,6-naphthalenedicarboxylicacid, 2,6-naphthalenedicarboxylate ester, terephthalic acid, anddimethyl terephthalate. Such additional dicarboxylic acids includearomatic dicarboxylic acids preferably having 8 to 14 carbon atoms,aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, orcycloaliphatic dicarboxylic acids preferably having 8 to 12 carbonatoms. Examples of dicarboxylic acids to be included with2,6-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylate esterare: phthalic acid, isophthalic acid, cyclohexanediacetic acid,diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipicacid, fumaric acid, azelaic acid, sebacic acid,2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,resorcinoldiacetic acid, diglycolic acid, 4,4'-oxybis(benzoic) acid,biphenyldicarboxylic acid, 1,12-dodecanedicarboxylic acid,4,4'-sulfonyldibenzoic acid, 4,4'-methylenedibenzoic acid,trans-4,4'-stilbenedicarboxylic acid, and the like. It should beunderstood that use of the corresponding acid anhydrides, esters, andacid chlorides of these acids is included in the term "dicarboxylicacid". The polyester may be prepared from one or more of the abovedicarboxylic acids or esters.

Component (b) of the present invention is a diol or diamine. Suitablediols include cycloaliphatic diols preferably having 6 to 20 carbonatoms or aliphatic diols preferably having 3 to 20 carbon atoms.Specific examples of diols are: ethylene glycol, diethylene glycol,triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol,butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol,2,2-dimethyl-1,3-propanediol, 1,10-decanediol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, 3-methylpentanediol-(2,4),2-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3),2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3),hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene,2,2-bis-(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, and2,2-bis-(4-hydroxypropoxyphenyl)-propane.

The polyester may also contain small amounts of trifunctional ortetrafunctional comonomers such as trimellitic anhydride,trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and otherpolyester forming polyacids or diols generally known in the art.

Naphthalenedicarboxylic acid containing polyamides can be formed fromadipic acid, isophthalic acid, terephthalic acid, 1,3- or1,4-cyclohexanedicarboxylic acid, aliphatic diacids containing 6 to 12carbon atoms, aliphatic amino acids or lactams with 6 to 12 carbonatoms, 1,6-hexanediamine, meta- or para-xylylenediamine, 1,3- or1,4-cyclohexane(bis)methylamine, aliphatic diamines with 4 to 12 carbonatoms, and other polyamide forming diacids and diamines. The polymer maybe prepared from one or more of the above diols or diamines.

The polymer may also contain polycarbonate repeat units formed from thereaction of a carbonic acid derivative with a diol such as bisphenol A.The polymer may be a blend of the above-described polyesters,polyamides, polycarbonates, or polyesteramides.

Component (c) of the present invention is 0.1 to 5 mole percent,preferably 0.5 to 2 mole percent of a fluorescence quenching compound.Using more than 5 mole percent of the fluorescence quenching compoundhinders the crystallization of the polyester and results in inferiorphysical properties. The fluorescence quenching compound is acopolymerized aromatic ketone which is copolymerized in the polymerbackbone. The copolymerized aromatic ketone contains an aromatic ringselected from benzene, naphthalene and biphenyl.

At least two polymerizable groups are attached to the aromatic ring.Preferably, two polymerizable groups are attached to the aromatic ring.The polymerizable groups are carboxylic acids or esters and/or aliphatichydroxyl groups. The carboxylic ester has the formula: ##STR1## whereinR₃ is selected from a substituted and unsubstituted C₁ -C₆ alkyl groupand a substituted and unsubstituted phenyl group. C₁ -C₆ unsubstitutedand substituted alkyl groups represented by R₃ include straight orbranched chain fully saturated hydrocarbon radicals and thesesubstituted with one or more of the following: C₅ -C₇ cycloalkyl, and C₅-C₇ cycloalkyl substituted with one or two of C₁ -C₆ alkyl, C₁ -C₆alkoxy or halogen. The substituted phenyl groups represent such phenylgroups substituted by one or two of C₁ -C₆ alkyl. Preferably R₃ ismethyl.

The aliphatic hydroxyl group has the formula:

    (CH.sub.2).sub.n OH

wherein n is an integer from 1 to 6, preferably n is 2. Preferredaromatic ring compounds containing polymerizable groups are terephthalicacid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. The mostpreferred is 2,6-naphthalenedicarboxylic acid.

In addition to the copolymerizable groups, the aromatic ring contains atleast one acyl group which has the structure ##STR2## wherein R₄ isselected from unsubstituted and substituted C₁ -C₁₀ alkyl, unsubstitutedand substituted phenyl, and unsubstituted and substituted naphthylgroups. C₁ -C₁₀ unsubstituted and substituted alkyl groups representedby R₄ include straight or branched chain fully saturated hydrocarbonradicals and these substituted with one or more of the following: C₅ -C₇cycloalkyl, and C₅ -C₇ cycloalkyl substituted with one or two of C₁ -C₆alkyl, C₁ -C₆ alkoxy or halogen. The substituted phenyl groups mentionedabove, unless otherwise specified, represent such phenyl groupssubstituted by one or two of C₁ -C₆ alkyl. The alkyl, phenyl andnaphthyl groups of R₄ may contain any substituent thereon as long assuch substituents do not deleteriously effect the fluorescence quenchingof the copolymerized aromatic ketone. Examples of acyl groups includeacetyl, benzoyl, 1- or 2-naphthoyl, and propionyl. Preferred acyl groupsare benzoyl and 1- or 2-naphthoyl. The most preferred acyl group is thebenzoyl group (C₆ H₅ CO--).

The acyl groups can be attached to any of the unsubstituted positions onthe aromatic rings. Preferred copolymerizable aromatic ketones includedimethyl benzoylterephthalate (or benzoyl terephthalic acid), dimethyl1-benzoyl 2,6-naphthalenedicarboxylate, dimethyl 3-benzoyl2,6-naphthalenedicarboxylate, dimethyl 4-benzoyl2,6-naphthalenedicarboxylate, dimethyl 1-(2-naphthoyl)2,6-naphthalenedicarboxylate, dimethyl dibenzoyl-2,6-naphthalenedicarboxylate, and dimethyl benzoylisophthalate. The most preferredcopolymerizable aromatic ketones are dimethyl benzoylterephthalate,dimethyl benzoyl-2,6-naphthalenedicarboxylate, and dimethyldibenzoyl-2,6-naphthalenedicarboxylate.

Many other ingredients can be added to the compositions of the presentinvention to enhance the performance properties of the polyester. Forexample, surface lubricants, denesting agents, stabilizers,antioxidants, ultraviolet light absorbing agents, mold release agents,metal deactivators, colorants such as black iron oxide and carbon black,nucleating agents, phosphate stabilizers, zeolites, fillers, and thelike, can be included herein. All of these additives and the use thereofare well known in the art. Any of these compounds can be used so long asthey do not hinder the present invention from accomplishing its objects.

The naphthalenedicarboxylic acid containing polymer with thefluorescence quenching compound is prepared by conventionalpolycondensation procedures well-known in the art which generallyinclude a combination of melt phase and solid state polymerization. Meltphase describes the molten state of the naphthalenedicarboxylic acidcontaining polymer during the initial polymerization process. Theinitial polymerization process includes direct condensation of thenaphthalenedicarboxylic acid with the diol or diamine or by esterinterchange using naphthalenedicarboxylic ester. For example,dimethyl-2,6-naphthalenedicarboxylate is ester interchanged withethylene glycol at elevated temperatures in the presence of thecopolymerizable aromatic ketone and a catalyst. The melt phase isconcluded by extruding the naphthalenedicarboxylic acid polymer intostrands and pelletizing. Optionally, the copolymerizable aromatic ketonecan be melt blended with the naphthalenedicarboxylic acid containingpolymer.

The naphthalenedicarboxylic acid containing polymer with thefluorescence quenching compound may optionally be solid statepolymerized. Solid state polymerization involves heating the polymerpellets to a temperature in excess of 200° C., but well below thecrystalline melt point, either in the presence of an inert gas stream orin a vacuum to remove a diol. Several hours are generally required inthe solid state polymerized unit to build the molecular weight.

Typical catalysts which may be used include titanium alkoxides, dibutyltin dilaurate, combinations of zinc, manganese, or magnesium acetates orbenzoates with antimony oxide or antimony triacetate.

The inherent viscosity of the naphthalenedicarboxylic acid containingpolymer should be 0.3 to 1.5 dL/g. However, inherent viscosities of from0.5 to 0.9 are preferred, as measured at 25° C. using 0.50 grams ofpolymer per 100 ml of a solvent consisting of 60% by weight phenol and40% by weight tetrachloroethane.

The naphthalenedicarboxylic acid containing polymer compositions serveas excellent starting materials for the production of moldings of alltypes. The naphthalenedicarboxylic acid containing polymers may also beblended with other polymers. Specific applications include foodpackaging such as bottles, trays, lids and films, medical parts,appliance parts, automotive parts, tool housings, recreational andutility parts. The molding compositions of the present invention areespecially useful in applications that require transparent molded parts.Additionally, the polymers can be used to prepare extruded sheets forthermoforming applications. The polymers are readily extruded into filmsor processed into monolayer or multilayer food and beverage containers.Potential methods for producing containers include: (1) injectionstretch blow molding using either one or two stage technology, (2)injection blow molding, (3) extrusion blow molding, (4) pipe extrusion,and (5) co-injection or coextrusion where the polymers can serve aseither the structural layer or barrier layer depending upon end userequirements. Fibers, melt-blown webs, extruded sheets, vacuum-drawntrays/parts, Injection molded parts, and extrusion coated wires may alsobe made from these polymers.

The materials and testing procedures used for the results shown hereinare as follows:

Fluorescence Intensity was determined using a Perkin-Elmer LS5BLuminescence Spectrometer which measured relative fluorescence intensityat peak maxima.

The composition of the polymers was determined using H-NMR spectroscopy(JEOL 270 Mhz). Solutions (2.5% weight/volume) in 70/30 CDCl_(3/)CF3COOD were scanned 256 times. A delay of 10 seconds was used with apulse width of 3.4 microseconds (5.0 microseconds, 90°).

Glass transition temperature (Tg), melting temperature (Tm) andcrystallization half-time (t_(1/2)) were determined by differentialscanning calorimetry (DSC) using a Perkin-Elmer DSC II instrument. TheTg and Tm were determined using a 20° C./minute scan rate after thesamples had been heated above the Tm and quenched below the Tg. Thet_(1/2) was determined by the following method: The sample was heated to300° C. under a nitrogen atmosphere and held for two minutes. The samplewas removed from the DSC and immediately cooled to -20° C. The DSC wascooled to 50° C. and the sample was returned to the DSC. The temperatureof the DSC was increased at a rate of 320° C./minute to a testtemperature of 190° C., 210° C. or 230° C. Samples were isothermallycrystallized at each of the test temperatures. The crystallizationhalf-time (t_(1/2)) is the time required to reach the peak on thecrystallization exotherm.

Inherent viscosity (I.V.) was measured at 25° C. using 0.50 grams ofpolymer per 100 ml of a solvent consisting of 60% by weight phenol and40% by weight tetrachloroethane.

Sample preparation for determining fluorescence intensity involvedgrinding the polyester samples to 3-4 mm. The samples weremicropulverized in an analytical grinding mill and passed through a 120mesh screen. The powders were dried for 24 hours at 140° C.Approximately 0.5 grams of the powder was packed into a sample holderand measurements were taken by reflectance. The excitation wavelengthwas 350 nm and the emission maximum was 428-432 nm unless listedotherwise. The values are reported as normalized topoly(ethylene-2,6-naphthalenedicarboxylate) (fluorescence intensity100). The fluorescence intensity ofpoly(ethylene-2,6-naphthalenedicarboxylate) was repeated 10 times with astandard deviation of 5.0. Two measurements were taken of all othersamples and the averages are reported in Table I.

The present invention will be further illustrated by a consideration ofthe following examples, which are intended to be exemplary of theinvention. All parts and percentages in the examples are on a weightbasis unless otherwise stated.

EXAMPLE 1

Poly(ethylene 2,6-naphthalene dicarboxylate) was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.5 moles, 122 grams), ethyleneglycol (1.0 moles, 62 grams), and catalyst metals were placed in a 500mL polymerization reactor under a nitrogen atmosphere. The mixture washeated with stirring at 200° C. for 2 hours. The temperature wasincreased to 220° C. and maintained for 1 hour. The temperature wasincreased to 290° C. which took approximately 20 minutes. When thetemperature reached 290° C., the nitrogen flow was stopped and vacuumwas applied. The polymer was stirred under vacuum (0.1-0.3 mm Hg) for 50minutes. The polymer was cooled and ground. The fluorescence intensityand I.V. of the polymer are summarized in Table I, and Tg, Tm andt_(1/2) are listed in Table II.

EXAMPLE 2

Poly(ethylene 2,6-naphthalene dicarboxylate) with 0.5 mole percentcopolymerized dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.124 moles, 30.35 grams),dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate (0.00063 moles, 0.22grams), ethylene glycol (0.25 moles, 15.5 grams), and catalyst metalswere placed in a 100 mL polymerization reactor under a nitrogenatmosphere. The polymer was prepared according to the procedure as setforth in Example 1. The fluorescence intensity and I.V. of the polymerare summarized in Table I, and t_(1/2) are listed in Table II.

EXAMPLE 3

Poly(ethylene 2,6-naphthalene dicarboxylate) with 1.0 mole percentcopolymerized dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.124 moles, 30.35 grams),dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate (0.00125 moles, 0.44grams), ethylene glycol (0.25 moles, 15.5 grams), and catalyst metalswere placed in a 100 mL polymerization reactor under anitrogen-atmosphere. The polymer was prepared according to the procedureas set forth in Example 1. The fluorescence intensity and I.V. of thepolymer are summarized in Table I, and t_(1/2) are listed in Table II.

EXAMPLE 4

Poly(ethylene 2,6-naphthalene dicarboxylate) with 2.0 mole percentcopolymerized dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.123 moles, 29.98 grams),dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate (0.0025 moles, 0.87grams), ethylene glycol (0.25 moles, 15.5 grams), and catalyst metalswere placed in a 100 mL polymerization reactor under a nitrogenatmosphere. The polymer was prepared according to the procedure as setforth in Example 1. The fluorescence intensity and I.V. of the polymerare summarized in Table I, and Tg, Tm are listed in Table II.

EXAMPLE 5

Poly(ethylene 2,6-naphthalene dicarboxylate) with 5.0 mole percentcopolymerized dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.119 moles, 28.98 grams),dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate (0.00625 moles, 2.18grams), ethylene glycol (0.25 moles, 15.5 grams), and catalyst metalswere placed in a 100 mL polymerization reactor under a nitrogenatmosphere. The polymer was prepared according to the procedure as setforth in Example 1. The fluorescence intensity and I.V. of the polymerare summarized in Table I, and Tg are listed in Table II.

EXAMPLE 6

Poly(ethylene 2,6-naphthalene dicarboxylate) with 1.2 mole percentcopolymerized dimethyl benzoylterephthalate was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.495 moles, 120.78 grams),dimethyl benzoylterephthalate (0.0058 moles, 1.74 grams), ethyleneglycol (1.0 mole, 62.0 grams), and catalyst metals were placed in a 500mL polymerization reactor under a nitrogen atmosphere. The polymer wasprepared according to the procedure as set forth in Example 1. Thefluorescence intensity and I.V. of the polymer are summarized in TableI, and t_(1/2) are listed in Table II.

EXAMPLE 7

Poly(ethylene 2,6-naphthalene dicarboxylate) with 2.0 mole percentcopolymerized dimethyl benzoylterephthalate was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.49 moles, 119.56 grams),dimethyl benzoylterephthalate (0.010 moles, 2.98 grams), ethylene glycol(1.0 mole, 62.0 grams), and catalyst metals were placed in,a 500 mLpolymerization reactor under a nitrogen atmosphere. The polymer wasprepared according to the procedure as set forth in Example 1. Thefluorescence intensity and I.V. of the polymer are summarized in TableI, and t_(1/2) are listed in Table II.

EXAMPLE 8

Poly(ethylene 2,6-naphthalene dicarboxylate) with 3.5 mole percentcopolymerized dimethyl benzoylterephthalate was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.483 moles, 117.7 grams),dimethyl benzoylterephthalate (0.018 moles, 5.22 grams), ethylene glycol(1.00 mole, 62.0 grams), and catalyst metals were placed in a 500 mLpolymerization reactor under a nitrogen atmosphere. The polymer wasprepared according to the procedure as set forth in Example 1. Thefluorescence intensity and I.V. of the polymer are summarized in TableI, and t_(1/2) are listed in Table II.

EXAMPLE 9

Poly(ethylene 2,6-naphthalene dicarboxylate) with 5.0 mole percentcopolymerized dimethyl benzoylterephthalate was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalene dicarboxylate (0.475 moles, 115.90 grams),dimethyl benzoylterephthalate (0.025.moles, 7.45 grams), ethylene glycol(1.00 mole, 62.0 grams), and catalyst metals were placed in a 500 mLpolymerization reactor under a nitrogen atmosphere. The polymer wasprepared according to the procedure as set forth in Example 1. Thefluorescence intensity and I.V. of the polymer are summarized in TableI, and t_(1/2) are listed in Table II.

EXAMPLE 10

Poly(ethylene 2,6-naphthalene dicarboxylate) with 0.5 mole percentcopolymerized dimethyl 1-(2-naphthoyl)-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl-2,6-naphthalene dicarboxylate (0.124 moles, 30.35 grams),dimethyl 1-(2-naphthoyl)-2,6-naphthalene dicarboxylate (0.00063 moles,0.25 grams), ethylene glycol (0.25 mole, 15.5 grams), and catalystmetals were placed in a 100 mL polymerization reactor under a nitrogenatmosphere. The polymer was prepared according to the procedure as setforth in Example 1. The fluorescence intensity and I.V. of the polymerare summarized in Table I, and Tg and Tm are listed in Table II.

EXAMPLE 11

Poly(ethylene 2,6-naphthalene dicarboxylate) with 1.0 mole percentcopolymerized dimethyl 1-(2-naphthoyl)-2,6-naphthalene dicarboxylate wasprepared by the following procedure.

Dimethyl-2,6-naphthalene dicarboxylate (0.124 moles, 30.20 grams),dimethyl 1-(2-naphthoyl)-2,6-naphthalene dicarboxylate (0.00125 moles,0.50 grams), ethylene glycol (0.25 mole, 15.5 grams), and catalystmetals were placed in a 100 mL polymerization reactor under a nitrogenatmosphere. The polymer was prepared according to the procedure as setforth in Example 1. The ,fluorescence intensity and I.V. of the polymerare summarized in Table I, and Tg and Tm are listed in Table II.

                                      TABLE I                                     __________________________________________________________________________                               FLUORESCENCE                                              AROMATIC KETONE I.V.                                                                              INTENSITY                                          EXAMPLE                                                                              (mole %)        (dL/g)                                                                            (at 430 nm)                                        __________________________________________________________________________    1      PEN control     0.42                                                                              100                                                2      PEN + 0.5% 1-benzoyl-DMN.sup.1                                                                0.48                                                                              47                                                 3      PEN + 1.0% 1-benzoyl-DMN.sup.1                                                                0.47                                                                              33                                                 4      PEN + 2.0% 1-benzoyl-DMN.sup.1                                                                0.43                                                                              26                                                 5      PEN + 5.0% 1-benzoyl-DMN                                                                      0.45                                                                              13                                                 6      PEN + 1.2% benzoy,-DMT.sup.2                                                                  0.38                                                                              79                                                 7      PEN + 2.0% benzoyl-DMT.sup.2                                                                  0.42                                                                              62                                                 8      PEN + 3.5% benzoyl-DMT.sup.2                                                                  0.44                                                                              62                                                 9      PEN + 5.0% benzoyl-DMT.sup.2                                                                  0.39                                                                              43                                                 10     PEN + 0.5% 1-(2-naphthoyl)-N.sup.3                                                            0.35                                                                              40                                                 11     PEN + 1.0% 1-(2-naphthoyl)-N.sup.3                                                            0.39                                                                              28                                                 __________________________________________________________________________     .sup.1 dimethyl 1benzoyl-2,6-naphthalene dicarboxylate                        .sup.2 dimethyl benzoylterephthalate                                          .sup.3 1(2-naphthoyl)-2,6-naphthalene dicarboxylate                      

The results in Table I clearly indicate that thepoly(ethylene-2,6-naphthalene dicarboxylate) compositions containing acritical range of an aromatic ketone as a fluorescence quencher, whichis copolymerized in the PEN backbone, exhibit significantly lessfluorescence than PEN compositions without the fluorescence quencher. Inaddition, the data in Table I also indicates that the use of thefluorescence quencher in a critical amount does not deleteriously effectthe inherent viscosity of the polyester.

                                      TABLE II                                    __________________________________________________________________________           AROMATIC KETONE Tg Tm t.sub.1/2  (min.)                                EXAMPLE                                                                              (mole %)        (°C.)                                                                     (°C.)                                                                     190° C.                                                                    210° C.                                                                    230° C.                           __________________________________________________________________________    1      PEN control     123                                                                              268                                                                              2.5 1.5 2.5                                      2      PEN + 0.5% 1-benzoyl-DMN.sup.1                                                                -- -- 5.7 3.7 5.8                                      3      PEN + 1.0% 1-benzoyl-DMN.sup.1                                                                -- -- 6.0 4.2 7.9                                      4      PEN + 2.0% 1-benzoyl-DMN.sup.1                                                                123                                                                              262                                                                              --  --  --                                       5      PEN + 5.0% 1-benzoyl-DMN.sup.1                                                                126                                                                              -- --  --  --                                       6      PEN + 1.2% benzoyl-DMT.sup.2                                                                  -- -- 3.0 1.9 3.1                                      7      PEN + 2.0% benzoyl-DMT.sup.2                                                                  -- -- 3.9 2.6 4.9                                      8      PEN + 3.5% benzoyl-DMT.sup.2                                                                  -- -- 3.8 2.8 6.3                                      9      PEN + 5.0% benzoyl-DMT.sup.2                                                                  -- -- 4.0 3.3 8.8                                      10     PEN + 0.5% 1-(2-naphthoyl)-N.sup.3                                                            122                                                                              266                                                                              --  --  --                                       11     PEN + 1.0% 1-(2-naphthoyl)-N.sup.3                                                            124                                                                              266                                                                              --  --  --                                       __________________________________________________________________________     .sup.1 dimethyl 1benzoyl-2,6-naphthalene dicarboxylate                        .sup.2 dimethyl benzoylterephthalate                                          .sup.3 1(2-naphthoyl)-2,6-naphthalene dicarboxylate                      

The results in Table II establish the critical range for the aromaticketones as fluorescence quenchers which are copolymerized in thepoly(ethylene-2,6-naphthalene dicarboxylate) backbone. The dataindicates that 0.1 to 5 mole percent of the aromatic ketones reducefluorescence without deleteriously effecting the physical properties ofthe polyester. In contrast, greater than 5 mole percent of the aromaticketones in the compositions slows down the crystallization rate to anunacceptable level.

EXAMPLE 12

Preparation of industrial scale poly(ethylene 2,6-naphthalenedicarboxylate) with 1.0 mole percent copolymerized dimethyl1-benzoyl-2,6-naphthalene dicarboxylate was prepared by the followingprocedure.

Dimethyl 2,6-naphthalene dicarboxylate (28.1 moles, 6.86 kilograms),dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate (0.28 moles, 96.6grams), ethylene glycol (56.3 moles, 3.49 kilograms), and catalystmetals were placed in a 10 gallon steel polymerization reactor equippedwith a twin-blade helical agitator under a nitrogen atmosphere. Themixture was heated with stirring at 200° C. for 2 hours. The temperaturewas increased to 220° C. and maintained for 2 hours. The temperature wasincreased to 285° C. When the temperature reached 285° C., the nitrogenflow was stopped and vacuum was applied. The polymer was stirred undervacuum (0.5 mm Hg) for 50 minutes. The polymer was extruded into a waterbath and pelletized. The amorphous polymer was transferred to a vacuumoven and dried for three hours at 80° C. Crystallization wasaccomplished in a tumbler crystallizer for three hours at 180° C. TheI.V. of the polymer at this stage was 0.59 dL/g.

To increase the molecular weight of the polymer, solid-statepolymerization was utilized. The crystalline polymer was charged to astationary bed solid-state unit equipped with nitrogen flow. The polymerwas heated to 230° C. The temperature was maintained for 24 hours in thepresence of a nitrogen purge. The I.V. of the polymer at this stage was0.71 dL/g. The fluorescence intensity of the polymer was 50 as comparedto 135 for similarly prepared PEN containing no fluorescence quencher.

EXAMPLE 13

A two-stage stretch blow molding process was utilized to make 2-literbottles. Preforms were made on a Cincinnati Milacron injection moldingmachine at a molding temperature of 310° C. The preforms were stored for24 hours before the bottle blowing step. Bottles were blown by reheatingpreforms using a quartz lamp by stretch blow molding or reheat blowmolding. The preforms were heated slightly above the Tg of the polymerand pressurized to blow them into bottle shaped molds.

Visual inspection indicated that bottles prepared from PEN without afluorescence quencher exhibited more bluish fluorescence than bottlesprepared using PEN with 1.0 mole percent copolymerized dimethyl1-benzoyl-2,6-naphthalene dicarboxylate.

EXAMPLE 14

Dimethyl 1-benzoyl-2,6-naphthalene dicarboxylate was prepared by thefollowing procedure.

2,6-dimethyl naphthalene (100 grams, 0.64 moles), aluminum chloride(89.3 grams, 0.67 moles), carbon disulfide (600 mL), and methylenechloride (200 mL) were introduced into a 3-neck 2L flask fitted with amechanical stirrer and cooled to 0°-5° C. Benzoyl chloride (94.2 grams,0.67 moles) was added dropwise over a period of about 1 hour. Thetemperature was kept below 10° C. during this addition and throughoutthe reaction. The reaction mixture was stirred for 6 hours and thendecomposed by pouring into ice/HCl. The organic layer was washed 5 timeswith water and then dried for 12 hours over sodium sulfate. The organiclayer was concentrated to a viscous oil and treated with methanol,precipitating 1-benzoyl-2,6-dimethylnaphthalene as an off-white solid.The 1-benzoyI-2,6-dimethylnaphthalene was collected and dried (105grams, 63%). The 1-benzoyl-2,6-dimethylnaphthalene was determined to bepure by gas chromatography with a melting point of 81°-82° C.(literature mp 84° C.). A molecular weight of 260 was confirmed by FieldDesorption Mass Spectroscopy (FDMS).

The 1-benzoyl-2,6-dimethylnaphthalene was oxidized to1-benzoyl-2,6-naphthalenedicarboxylic acid by the following procedure.

The 1-benzoyl-2,6-dimethylnaphthalene (60 grams, 0.23 moles), sodiumdichromate (185 grams, 0.621 moles), and 500 mL water were added to a 1liter high pressure autoclave. The high pressure oxidation was carriedout for 6 hours at 250° C. with stirring. Chromium oxide was filteredoff. Filtrate acidification with HCl resulting in precipitation of alight yellow material (67 g, 90%) which was used on the next stepwithout further purification. The 1-benzoyl-2,6-naphthalenedicarboxylicacid had a melting point over 315° C. and FDMS confirmed molecularweight of 320.

The 1-benzoyl-2,6-naphthalenedicarboxylic acid was converted to itsdimethyl ester by the following procedure.

The 1-benzoyl-2,6-naphthalenedicarboxylic acid (100 grams, 0.313 moles)and methanol (600 mL) were placed in a 1 liter high pressure autoclavefitted with a magnetic stirrer. High pressure esterification was carriedout for 2 hours at 250° C. with stirring. The reaction mixture wasconcentrated to dryness. A light brown solid was the result.Recrystallization from methanol followed with treatment with activatedcarbon in acetone which was repeated three times afforded (uponconcentration) 75 grams (69%) of almost white dimethyl1-benzoyl-2,6-naphthalene dicarboxylate. The dimethyl1-benzoyl-2,6-naphthalene dicarboxylate was gas chromatography pure witha melting point of 135°-137° C. FDMS confirmed a molecular weight of 348and a H-NMR spectrum consistent with the stated structure.

EXAMPLE 15

Poly(ethylene terephthalate) containing 5 mole percent copolymerizeddimethyl 2,6-naphthalenedicarboxylate was prepared by the followingprocedure.

Dimethyl terephthalate (0.713 mol, 138.2 g), dimethyl2,6-naphthalenedicarboxylate (0.0375 mol, 9.15 g), ethylene glycol (1.5mol, 93.0 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 90 min. The temperature was increased to 220° C.and maintained for 90 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3 mm Hg) for 30 minutes. The polymer was cooledand ground. The polymer had 0.43 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 16

Poly(ethylene terephthalate) containing 5 mole percent copolymerizeddimethyl 2,6-naphthalenedicarboxylate and 1.0 mole percent copolymerizeddimethyl 1-benzoyl-2,6-naphthalenedicarboxylate was prepared by thefollowing procedure.

Dimethyl terephthalate (0.705 mol, 136.7 g), dimethyl2,6-naphthalenedicarboxylate (0.0375 mol. 9.15 g), ethylene glycol (1.5mol, 93.0 g), dimethyl 1-benzoyl-2,6-naphthalenedicarboxylate (0.0075mol, 2.40 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 90 min. The temperature was increased to 220° C.and maintained for 90 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3 mm Hg) for 25 minutes. The polymer was cooledand ground. The polymer had 0.40 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 17

Poly(ethylene terephthalate) containing 25 mole percent copolymerizeddimethyl 2,6-naphthalenedicarboxylate was prepared by the followingprocedure.

Dimethyl terephthalate (0,563 mol, 109.1 g), dimethyl2,6-naphthalenedicarboxylate (0.187 mol, 45.7 g), ethylene glycol (1.5mol, 93.0 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 90 min. The temperature was increased to 220° C.and maintained for 90 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3 mm Hg) for 24 minutes. The polymer was cooledand ground. The polymer had 0.36 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 18

Poly(ethylene terephthalate) containing 25 mole percent copolymerizeddimethyl 2,6-naphthalenedicarboxylate and 1.0 mole percent copolymerizeddimethyl

1-benzoyl-2,6-naphthalenedicarboxylate was prepared by the followingprocedure.

Dimethyl terephthalate (0.555 mol, 107.6 g), dimethyl2,6-naphthalenedicarboxylate (0.187 mol. 45.7 g), ethylene glycol (1.5mol, 93.0 g), dimethyl 1-benzoyl-2,6-naphthalenedicarboxylate (0.0075mol, 2.40 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 90 min. The temperature was increased to 220° C.and maintained for 90 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3 mm Hg) for 28 minutes. The polymer was cooledand ground. The polymer had 0.45 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 19

Poly(butylene 2,6-naphthalenedicarboxylate) containing 30 mole percentcopolymerized 1,4-cyclohexanedimethanol was prepared by the followingprocedure.

Dimethyl 2,6-naphthalenedicarboxylate (0.5 mol, 122.0 g), 1,4-butanediol(0.7 mol, 63.0 g), 1,4-cyclohexanedimethanol (0.15 mol, 21.6 g) andcatalyst metals were placed in a 0.5L polymerization reactor under anitrogen atmosphere. The mixture was heated with stirring at 200° C. for90 min. The temperature was increased to 220° C. and maintained for 90min. The temperature was increased to 260° C., the nitrogen flow wasstopped and vacuum was applied. The polymer was stirred under vacuum(0.3-0.5 mm Hg) for 8 minutes. The polymer was cooled and ground. Thepolymer had 0.41 dL/g I.V. Fluorescence data are summarized in TableIII.

EXAMPLE 20

Poly(butylene 2,6-naphthalenedicarboxylate) containing 30 mole percentcopolymerized 1,4-cyclohexanedimethanol and 1.0 mole percentcopolymerized dimethyl 1-benzoyl-2,6-naphthalenedicarboxylate wasprepared by the following procedure.

Dimethyl 2,6-naphthalenedicarboxylate (0.495 mol, 120.8 g),1,4-butanediol (0.7 mol, 63.0 g), 1,4-cyclohexanedimethanol (0.15 mol,21.6 g), dimethyl 1-benzoyl-2,6-naphthalenedicarboxylate (0.005 mol,1.60 g) and catalyst metals were placed in a 0.5L polymerization reactorunder a nitrogen atmosphere. The mixture was heated with stirring at200° C. for 90 min. The temperature was increased to 220° C. andmaintained for 90 min. The temperature was increased to 260° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3-0.5 mm Hg) for 8 minutes. The polymer wascooled and ground. The polymer had 0.42 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 21

Poly(butylene 2,6-naphthalenedicarboxylate) was prepared by thefollowing procedure.

Dimethyl 2,6-naphthalenedicarboxylate (0.5 mol, 122.0 g), 1,4-butanediol(1.0 mol, 90.1 g), and catalyst metals were placed in a 0.5Lpolymerization reactor under a nitrogen atmosphere. The mixture washeated with stirring at 200° C. for 90 min. The temperature wasincreased to 220° C. and maintained for 90 min. The temperature wasincreased to 285° C., the nitrogen flow was stopped and vacuum wasapplied. The polymer was stirred under vacuum (0.3 mm Hg) for 5 minutes.The polymer was cooled and ground. The polymer had 0.62 dL/g I.V.Fluorescence data are summarized in Table III.

EXAMPLE 22

Poly(ethylene 2,6-naphthalenedicarboxylate) containing 25 mole percentcopolymerized dimethyl terephthalate was prepared by the followingprocedure.

Dimethyl 2,6-naphthalenedicarboxylate (0.563 mol, 137.3 g), dimethylterephthalate (0.187 mol, 36.4 g), ethylene glycol (1.5 mol, 93.0 g),and catalyst metals were placed in a 0.5L polymerization reactor under anitrogen atmosphere. The mixture was heated with stirring at 200° C. for90 min. The temperature was increased to 220° C. and maintained for 90min. The temperature was increased to 285° C. the nitrogen flow wasstopped and vacuum was applied. The polymer was stirred under vacuum(0.3 mm Hg) for 25 minutes. The polymer was cooled and ground. Thepolymer had 0.38 dL/g I.V. Fluorescence data are summarized in TableIII.

EXAMPLE 23

Poly(ethylene 2,6-naphthalenedicarboxylate) containing 50 mole percentcopolymerized dimethyl terephthalate was prepared by the followingprocedure.

Dimethyl 2,6-naphthalenedicarboxylate (0.375 mol, 91.5 g), dimethylterephthalate (0.375 mol, 72.7 g), ethylene glycol (1.5 mol, 93.0 g),and catalyst metals were placed in a 0.5L polymerization reactor under anitrogen atmosphere. The mixture was heated with stirring at 200° C. for90 min. The temperature was increased to 220° C. and maintained for 90min. The temperature was increased to 285° C. the nitrogen flow wasstopped and vacuum was applied. The polymer was stirred under vacuum(0.3 mm Hg) for 30 minutes. The polymer was cooled and ground. Thepolymer had 0.39 dL/g I.V. Fluorescence data are summarized in TableIII.

EXAMPLE 24

Poly(ethylene terephthalate) was prepared by the following procedure.

Dimethyl terephthalate (0.75 mol, 145.5 g), ethylene glycol (1.5 mol,93.0 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 60 min. The temperature was increased to 215° C.and maintained for 60 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3-0.5 mm Hg) for 30 minutes. The polymer wascooled and ground. The polymer had 0.35 dL/g I.V. Fluorescence data aresummarized in Table III.

EXAMPLE 25

Poly(ethylene terephthalate) containing 1 mole percent copolymerizeddimethyl 2,6-naphthalenedicarboxylate was prepared by the followingprocedure.

Dimethyl terephthalate (0.743 mol, 144.1 g), dimethyl2,6-naphthalenedicarboxylate (0.0075 mol, 1.83 ), ethylene glycol (1.5mol, 93.0 g), and catalyst metals were placed in a 0.5L polymerizationreactor under a nitrogen atmosphere. The mixture was heated withstirring at 200° C. for 90 min. The temperature was increased to 220° C.and maintained for 90 min. The temperature was increased to 285° C., thenitrogen flow was stopped and vacuum was applied. The polymer wasstirred under vacuum (0.3 mm Hg) for 40 minutes. The polymer was cooledand ground. The polymer had an I.V. of 0.51 dL/g. Fluorescence data aresummarized in Table III.

                  TABLE III                                                       ______________________________________                                                                     Relative                                                                              Maximum                                                      Aromatic Fluore- Wave-                                         Polymer        Ketone   scence  length                                   EX.  Composition    (mole %) Intensity                                                                             (nm)                                     ______________________________________                                        15   PET + 5% DMN   None     181     383                                      16   PET + 5% DMN   1% BzN   26      385                                      17   PET + 25% DMN  None     85      418                                      18   PET + 25% DMN  1% BzN   26      419                                      19   PBN + 30% CHDM None     64      421                                      20   PBN + 30% CHDM 1% BzN   29      431                                      21   PBN            None     74      428                                      22   PEN + 25% DMT  None     110     429                                      23   PEN + 50% DMT  None     102     431                                      24   PET            None     21      388                                      25   PET + 1% DMN   None     241     380                                      ______________________________________                                         DMN = dimethyl 2,6naphthalenedicarboxylate                                    BzN = dimethyl 1benzoyl-2,6-naphthalenedicarboxylate                          PBN = poly(butylene 2,6naphthalenedicarboxylate)                              CHDM = 1,4cyclohexanedimethanol                                               PET = poly(ethylene terephthalate)                                       

The results in Table III clearly indicate that naphthalenedicarboxylicacid containing polymers have a significant fluorescence intensity evenwhen naphthalenedicarboxylic acid is a minor component. Unexpectedly,PET copolymerized with as little as 1 mole percentnaphthalenedicarboxylate has a greater fluorescence intensity than PENhomopolymer. The results also indicate that the aromatic ketoneadditives of this invention effectively reduce fluorescence intensity ina broad composition range of naphthalenedicarboxylic acid containingpolymers.

Many variations will suggest themselves to those skilled in this art inlight of the above detailed description. All such obvious modificationsare within the full intended scope of the appended claims.

What is claimed is:
 1. A naphthalenedicarboxylic acid containing polymercomposition with reduced fluorescence comprising repeat units from:(a) adicarboxylic acid component which comprises 0.1 to less than 85 molepercent of 2,6-naphthalenedicarboxylic acid or2,6-naphthalenedicarboxylate esters; (b) a diol or diamine component;and (c) 0.1 to 5 mole percent, based on 100 mole percent dicarboxylicacid and 100 mole percent diol or diamine, of a nonhalogenatedcopolymerizable aromatic compound selected from the group consisting ofbenzene, naphthalene and biphenyl which has at least one acyl groupdirectly attached to the aromatic ring of said aromatic compound.
 2. Thecomposition of claim 1 wherein the diol component, component (b), is atleast 95 mole percent ethylene glycol.
 3. The composition of claim 1wherein the aromatic ring contains at least two polymerizable groupsselected from the group consisting of carboxylic esters, aliphatichydroxyl groups and combinations thereof.
 4. The composition of claim 3wherein the carboxylic ester has the formula: ##STR3## wherein R₃ isselected from the group consisting of a C₁ -C₆ alkyl group and a phenylgroup.
 5. The composition of claim 4 wherein the carboxylic ester is##STR4##
 6. The composition of claim 3 wherein the aliphatic hydroxylgroup has the formula:

    (CH.sub.2).sub.n OH

wherein n is an integer from 1 to
 6. 7. The composition of claim 5wherein the aliphatic hydroxyl group is (CH₂)₂ OH.
 8. The composition ofclaim 3 wherein the aromatic ring compound containing polymerizablegroups is selected from the group consisting of terephthalic acid,isophthalic acid, 2,6-naphthalenedicarboxylic acid and the esterderivatives thereof.
 9. The composition of claim 8 wherein the aromaticring compound containing polymerizable groups is2,6-naphthalenedicarboxylic acid.
 10. The composition of claim 1 whereinthe aromatic ring contains at least one acyl group of the formula##STR5## wherein R₄ is selected from the group consisting of C₁ -C₁₀alkyl, phenyl, and naphthyl group.
 11. The composition of claim 10wherein the acyl group is selected from the group consisting of acetyl,benzoyl, 1- or 2-naphthoyl, and propionyl.
 12. The composition of claim11 wherein the acyl group is C₆ H₅ CO--.
 13. The composition of claim 1wherein the copolymerizable aromatic compound is selected from the groupconsisting of dimethyl benzoylterephthalate, dimethyl 1-benzoyl2,6-naphthalenedicarboxylate, dimethyl 3-benzoyl2,6-naphthalenedicarboxylate, dimethyl 4-benzoyl2,6-naphthalenedicarboxylate, dimethyl 1- (2-naphthoyl )2,6-naphthalenedicarboxylate, dimethyl benzoylisophthalate, dimethyldibenzoyl-2,6-naphthalenedicarboxylate, and combinations thereof. 14.The composition of claim 13 wherein the copolymerizable aromaticcompound is dimethyl benzoylterephthalate.
 15. The composition of claim13 wherein the copolymerizable aromatic compound is dimethyl1-benzoyl-2,6-naphthalene dicarboxylate.
 16. The composition of claim 13wherein the copolymerizable aromatic compound is 1-(2-naphthoyl)-2,6-naphthalene dicarboxylate.